Most of the fires were ignited Sunday, driven by winds of up to 79 mph and dry conditions. The winds died down early this week, but gusts of 20 to 40 mph were seen Wednesday, the humidity was extremely low, and no rain is forecast for the next few days.

In hard-hit Sonoma County, Sheriff Rob Giordano said his office has received 600 reports of missing people, of which detectives have been able to locate 315 people. Giordano believes many of the 285 people who are unaccounted for will be located once telecommunications issues are solved, but he also fears more bodies will be found.

More than 20,000 people had been ordered to evacuate as of Wednesday, and authorities were encouraging others to pack “ready-to-go bags” with documents and medicines in case they had to flee the fast-spreading flames on a moment’s notice.

Giordano had a suggestion Wednesday for people who’d been advised to be prepared to leave: Go anyway.

“Traffic is bad in the county. If we have to evacuate people, it’d be better to have you (already) out of the area. If you have a place to go, go,” he said.

“We are very concerned about all the fire lines, because of the wind they’re anticipating,” he said.

Latest developments

• Wildfires have burned nearly 170,000 acres in California. The largest fires were in Northern California’s Sonoma, Napa and Mendocino counties, filling the picturesque landscape of the state’s wine country with charred rubble and clouds of smoke.

• Of the 21 people who have died since Sunday night, 11 were killed in the Tubbs wildfire in Sonoma County, officials said. That makes the Tubbs fire, one of 22 blazes burning in the state, the sixth-deadliest fire in recorded California history, authorities said.

• People who left evacuation zones in Sonoma County aren’t yet allowed to return, Giordano said.

• Officials said Wednesday that almost 8,000 firefighters are involved in trying to contain the blazes. The equipment being used includes 550 fire trucks — at least 170 of which came from out of state — 73 helicopters and more than 30 planes.

Scores missing

Families are frantically searching for those who have been reported missing. Authorities believe communications issues are preventing many of those people from checking in with relatives.

But one family’s search for a loved one in Santa Rosa ended tragically.

Christina Hanson, 28, who used a wheelchair and lived in an apartment next to her father’s house, was reported missing after the fire. Hanson had called her father’s ex-wife to say she saw flames, but no one had heard from her after that, her family said.

After a day of panic and uncertainty, Hanson’s cousin confirmed she had died in the fire.

Couple, 100 and 98, killed

Also among the dead were a couple who relatives said had known each other for nearly 90 years: Charles Rippey, 100, and his wife, Sara, 98.

They died shortly after the Atlas fire — now one of the largest, at more than 42,000 acres — began Sunday night, engulfing their home near the Silverado Country Club north of Napa, Napa County spokeswoman Kristi Jourdan said.

“This house was one of the first ones hit (in the subdivision),” their son Mike Rippey told CNN affiliate KPIX on Tuesday.

The couple met each other in grade school in Wisconsin and began a family together after Charles served in World War II, the son told KPIX. They relocated to California after living in the Midwest and on the East Coast, he said.

The son said he believed his father was trying to save his mother when the fire struck.”From where they found his body, he was trying to get from his room to her room,” he told KPIX. “He never made it. … There is no way he would have left (without her).”

Elsewhere in the county, part of a veterans home in Yountville, near Napa, was evacuated Tuesday night over fears of approaching flames, but the fire changed directions, so the rest of the residents will stay put for now, Napa Mayor Jill Techel said. Only the most frail — those in a nursing facility — left the property in the initial evacuation, Techel said.

“We are set up with buses and everything we need to do if we get the call that a part of town or a part of Napa needs to be evacuated,” Techel said.

Minutes to escape

The Tubbs fire reduced cars and homes into burnt piles of ash and rubble in parts of Santa Rosa, a city of about 175,000 roughly 50 miles northwest of San Francisco.

That fire has burned 27,363 acres and destroyed at least 576 structures between Santa Rosa and the Calistoga area, Cal Fire said Wednesday. It is 10% contained.

A large part of Santa Rosa was evacuated. In the city’s Coffey Park neighborhood, homes are in ruins — the fire seemed to consume everything that wasn’t steel, concrete or brick. At some properties, all that is recognizable are the remains of washers, dryers and water heaters.

Zach Block’s house is among those destroyed in Santa Rosa. He said he woke up early Monday to the smell of smoke.

He, his wife, his 11-month-old daughter and his brother escaped — but not before he tried to save the house.

“Within 10 minutes, my brother and I were out in the backyard with the hoses and trying to fight off as much as we could, and then we had to evacuate within five minutes of the fire touching down on the backyard,” he told CNN’s “New Day” on Wednesday.